content: /*
   * Copyright 2017 David Karnok
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package hu.akarnokd.reactive4javaflow.impl.operators;
  
  import hu.akarnokd.reactive4javaflow.*;
  import hu.akarnokd.reactive4javaflow.functionals.CheckedBiConsumer;
  import hu.akarnokd.reactive4javaflow.impl.*;
  
  import java.util.Objects;
  import java.util.concurrent.*;
  
  public final class FolyamCollect<T, C> extends Esetleg<C> {
  
      final Folyam<T> source;
  
      final Callable<C> collectionSupplier;
  
      final CheckedBiConsumer<C, ? super T> collector;
  
      public FolyamCollect(Folyam<T> source, Callable<C> collectionSupplier, CheckedBiConsumer<C, ? super T> collector) {
          this.source = source;
          this.collectionSupplier = collectionSupplier;
          this.collector = collector;
      }
  
      @Override
      protected void subscribeActual(FolyamSubscriber<? super C> s) {
  
          C initial;
  
          try {
              initial = Objects.requireNonNull(collectionSupplier.call(), "The collectionSupplier returned a null value");
          } catch (Throwable ex) {
              EmptySubscription.error(s, ex);
              return;
          }
  
          source.subscribe(new CollectSubscriber<>(s, initial, collector));
      }
  
      static final class CollectSubscriber<T, C> extends DeferredScalarSubscription<C> implements FolyamSubscriber<T> {
  
          final CheckedBiConsumer<C,? super T> collector;
  
          Flow.Subscription upstream;
  
          public CollectSubscriber(FolyamSubscriber<? super C> actual, C initial, CheckedBiConsumer<C, ? super T> collector) {
              super(actual);
              this.collector = collector;
              this.value = initial;
          }
  
  
          @Override
          public void onSubscribe(Flow.Subscription subscription) {
              upstream = subscription;
              actual.onSubscribe(this);
              subscription.request(Long.MAX_VALUE);
          }
  
          @Override
          public void onNext(T item) {
              C c = value;
              if (c != null) {
                  try {
                      collector.accept(c, item);
                  } catch (Throwable ex) {
                      value = null;
                      upstream.cancel();
                      error(ex);
                  }
              }
          }
  
          @Override
          public void onError(Throwable throwable) {
              if (value == null) {
                  FolyamPlugins.onError(throwable);
                  return;
              }
              value = null;
              error(throwable);
          }
  
          @Override
          public void onComplete() {
              C c = value;
              if (c != null) {
                  value = null;
                  complete(c);
              }
          }
      }
  }
  